This invention relates to an improved seat cushion support for use in a combination sofa sleeper having a foldable bed frame adapted to be collapsed and hidden in the bottom of a sofa frame.
Foldable sofa sleepers having pivotally interconnected head, body, intermediate, and foot sections movable between a fully folded or retracted position within the sofa frame and an extended position wherein the sections extend out and over the front rail of the sofa frame are known to the art. In such foldable sofa sleepers, in the extended position, the head, body, intermediate, and foot sections lie substantially coplanar one to the other providing a horizontal surface upon which a mattress is placed to provide a bed. In the folded sitting position of said foldable sofa sleepers, the body and foot sections of the sofa frames are located in parallel spaced horizontal planes interconnected by the substantially vertically poisitioned intermediate frame section. The bed mattress is folded substantially double between the foot and body sections of the frame in this folded position and the foldable frame and mattress are contoured and hidden within the sofa frame. Generally, cushions cover or are placed atop the folded mattress in this seating position of the sofa sleeper.
One criticism which has fairly been leveled against most convertible sofa sleepers is that they do not provide as comfortable a seating surface as a conventional non-convertible sofa. In general, this criticism is traceable to the fact that the cushion support, the folded mattress contained internally of the folded sofa sleeper tends to sag when a substantial weight is placed upon it. This "sag" results from the fact that the mattress supporting deck must be resilient or at least have some resiliency in order to provide a satisfactory sleeping surface, and this resiliency carries over to the seating position of the sofa sleeper wherein the resiliency is to be avoided in order to provide maximum comfort in the seating position.
One attempt to solve this problem of seat sag in the seating attitude of the sofa sleeper has been to stretch the matteess supporting canvas or fabric deck beneath the folded mattress when the sofa sleeper is folded into the sofa frame, thereby providing a taut support beneath the sofa cushions. Such an attempt for improving the seating surface of a sofa sleeper is disclosed and described in U.S. Pat. Nos. 2,352,989, 2,878,490, and 4,173,803.
Yet another attempt to solve this same problem is disclosed in U.S. Pat. No. 3,854,153. According to the disclosure of this patent, crossed tension wires are located beneath the intermediate section of the bed frame in an attempt to rigidify the support beneath the mattress when it is folded into the sofa frame and serves as a support for the seat cushions.
Up to the present time the solutions or partial solutions described in the patents identified hereinabove have substantially improved the seating characteristics of a convertible sofa sleeper. However, even with these improvements, the seating surfaces do not measure up to and are not as comfortable a seating surface as a non-convertible type sofa.
It has therefore been an objective of this invention to provide a sofa sleeper having a seating surface which is more comfortable than that heretofore provided in convertible sofa sleepers.
Still another objective of this invention has been to provide a more rigid and firm mattress support for a sofa sleeper when the mattress is folded into the sofa frame and functions as a support for seat cushions without detracting from the resiliency and comfort of the mattress support in the extended coplanar position of the mattress support.